Extratropical cyclones in a warmer, moister climate: A recent Atlantic analogue

Abstract

Current climate model projections do not exhibit a large change in the intensity of extratropical cyclones. However, there are concerns that current models represent moist processes poorly, and this provides motivation for investigating observational evidence for how cyclones behave in warmer climates. In the North Atlantic in particular, recent decades provide a clear contrast between warm and cold climates due to Atlantic Multidecadal Variability. In this paper we investigate these periods as analogues which may provide a guide to future cyclone behavior. While temperature and moisture rise in recent warm periods as in the projections, differences in energetics and temperature gradients imply that these periods are only partial analogues. The main result from current reanalyses is that while increased cyclone-associated precipitation is seen in the recent warm periods, there is no robust evidence of an increase in cyclone intensity by other measures, such as maximum wind speed or vorticity. A set of low-and high-resolution model simulations are also studied, suggesting that changes in cyclone intensity may be different in higher-resolution reanalyses.

Extratropical Cyclones in Idealized Simulations of Changed Climates

“…Similar results have been obtained in other recent studies using an analog approach (Li et al 2014) or idealized baroclinic channel simulations (Booth et al 2013). This is consistent with our findings, which also imply minor cyclone intensity variations for a comparably small range of temperature changes.…”

Trends in cyclones in the high‐latitude North Atlantic during 1979–2016

“…Despite reporting significant trends in cyclone occurrence for the time period 1979–2016, our results do not allow prediction of future changes in cyclones in our study region. In general, current climate models do not predict considerable intensification (deepening) of extratropical cyclones (Li et al ., ). This is, however, possibly due to challenges in modelling the factors affecting cyclone activity, which is sensitive to model resolution, atmosphere–ocean coupling, and parametrization of subgrid‐scale physical processes (Willison et al ., ).…”

“…Further, as Shepherd () writes, “we have much less confidence in the atmospheric circulation aspects of climate change [compared to the thermodynamic aspect], which are primarily controlled by dynamics and exert a strong control on regional climate”. Regarding cyclones being an important component of atmospheric dynamics, several studies have addressed the question of how cyclone activity has changed and will change in the future Arctic (Rinke et al ., ; Zhang et al ., ; Sepp and Jaagus, ; Li et al ., ; Koyama et al ., ; Zahn et al ., )…”

Variability of daily winter wind speed distribution over Northern Europe during the past millennium in regional and global climate simulations

“…Comparable difficulties are reported by FischerBruns et al (2005). All in all the expected link between the mean temperature and the wind speed distribution and between the mean temperature gradient and the wind speed distribution Li and Woollings (2014) is not confirmed in each simulation. In our study the three global simulations present similarities that warrant to place them in one group.…”

“…However, warmer periods are generally characterized by a weaker meridional temperature gradient due to the stronger warming of the high latitudes with respect to the tropics, and thus a weaker baroclinicity, which should lead to weaker or less storms (Li and Woollings, 2014;Yin, 2005). In addition, the North Atlantic Oscillation (NAO), as the main pattern of troposphere dynamics over the North Atlantic-European sector, is also related to the interannual variability of seasonal mean winds in this region.…”